Ordnance – Shields – Shape or composition
Reexamination Certificate
1999-05-18
2001-09-18
Johnson, Stephen M. (Department: 3641)
Ordnance
Shields
Shape or composition
C428S911000
Reexamination Certificate
active
06289781
ABSTRACT:
The present invention relates to composite armor plates and panels. More particularly, the invention relates to an armored plate which may be worn to provide the user with lightweight ballistic protection, as well as to armored plates for providing ballistic protection for light and heavy mobile equipment and vehicles against high-speed projectiles or fragments.
In U.S. Pat. No. 5,763,813 there is described a composite armor plate for absorbing and dissipating kinetic energy from high velocity, armor-piercing projectiles, said plate comprising a single internal layer of high density ceramic pellets which are directly bound and retained in plate form by a solidified material such that the pellets are bound in a plurality of superposed rows, characterized in that the pellets have an Al
2
O
3
content of at least 85%, preferably at least 93%, and a specific gravity of at least 2.5, the majority of the pellets each have at least one axis in the range of about 3-12 mm, and are bound by said solidified material in a single internal layer of superposed rows, wherein a majority of each of said pellets is in direct contact with at least 4 adjacent pellets, the total weight of said plate does not exceed 45 kg/m
2
and said solidified material and said plate are elastic.
In U.S. patent application Ser. No. 09/048,628 (now U.S. Pat. No. 6,112,635) there is described and claimed a composite armor plate for absorbing and dissipating kinetic energy from high velocity, armor-piercing projectiles, said plate comprising a single internal layer of high density ceramic pellets which are directly bound and retained in plate by a solidified material such that the pellets are bound in a plurality of adjacent rows, characterized in that the pellets have an Al
2
O
3
content of at least 93% and a specific gravity of at least 2.5, the majority of the pellets each have at least 12 mm length and are bound by said solidified material in a single internal layer of adjacent rows, wherein a majority of each of said pellets is in direct contact with at least 4 adjacent pellets, and said solidified material and said plate are elastic.
In U.S. Ser. No. 08/944,343 there is described and claimed a ceramic body for deployment in a composite armor panel, said body being substantially cylindrical in shape, with at least one convexly curved end face, wherein the ratio D/R between the diameter D of said cylindrical body and the radius R of curvature of said at least one convexly curved end face is at least 0.64:1.
The teachings of all three of these specifications is incorporated herein by reference.
There are four main considerations concerning protective armor panels. The first consideration is weight. Protective armor for heavy but mobile military equipment, such as tanks and large ships, is known. Such armor usually comprises a thick layer of alloy steel, which is intended to provide protection against heavy and explosive projectiles. However, reduction of weight of armor, even in heavy equipment, is an advantage since it reduces the strain on all the components of the vehicle. Furthermore, such armor is quite unsuitable for light vehicles such as automobiles, jeeps, light boats, or aircraft, whose performance is compromised by steel panels having a thickness of more than a few millimeters, since each millimeter of steel adds a weight factor of 7.8 kg/m
2
.
Armor for light vehicles is expected to prevent penetration of bullets of any type, even when impacting at a speed in the range of 700 to 1000 meters per second. However, due to weight constraints it is difficult to protect light vehicles from high caliber armor-piercing projectiles, e.g. of 12.7 and 14.5 mm, since the weight of standard armor to withstand such projectile is such as to impede the mobility and performance of such vehicles.
A second consideration is cost. Overly complex armor arrangements, particularly those depending entirely on synthetic fibers, can be responsible for a notable proportion of the total vehicle cost, and can make its manufacture non-profitable.
A third consideration in armor design is compactness. A thick armor panel, including air spaces between its various layers, increases the target profile of the vehicle. In the case of civilian retrofitted armored automobiles which are outfitted with internal armor, there is simply no room for a thick panel in most of the areas requiring protection.
A fourth consideration relates to ceramic plates used for personal and light vehicle armor, which plates have been found to be vulnerable to damage from mechanical impacts caused by rocks, falls, etc.
Fairly recent examples of armor systems are described in U.S. Pat. No. 4,836,084, disclosing an armor plate composite including a supporting plate consisting of an open honeycomb structure of aluminium; and U.S. Pat. No. 4,868,040, disclosing an antiballistic composite armor including a shock-absorbing layer. Also of interest is U.S. Pat. No. 4,529,640, disclosing spaced armor including a hexagonal honeycomb core member.
Other armor plate panels are disclosed in British Patents 1,081,464; 1,352,418; 2,272,272, and in U.S. Pat. No. 4,061,815 wherein the use of sintered refractory material, as well as the use of ceramic materials, are described.
Ceramic materials are nonmetallic, inorganic solids having a crystalline or glassy structure, and have many useful physical properties, including resistance to heat, abrasion and compression, high rigidity, low weight in comparison with steel, and outstanding chemical stability. Such properties have long drawn the attention of armor designers, and solid ceramic plates, in thicknesses ranging from 7 mm. for personal protection to 30 mm. for heavy military vehicles, are commercially available for such use.
Much research has been devoted to improving the low tensile and low flexible strength and poor fracture toughness of ceramic materials; however, these remain the major drawbacks to the use of ceramic plates and other large components which can crack and/or shatter in response to the shock of an incoming projectile.
Light-weight, flexible armored articles of clothing have also been used for many decades, for personal protection against fire-arm projectiles and projectile splinters. Examples of this type of armor are found in U.S. Pat. No. 4,090,005. Such clothing is certainly valuable against low-energy projectiles, such as those fired from a distance of several hundred meters, but fails to protect the wearer against high-velocity projectiles originating at closer range and especially does not protect against armor-piercing projectiles. If made to provide such protection, the weight and/or cost of such clothing discourages its use. A further known problem with such clothing is that even when it succeeds in stopping a projectile the user may suffer injury due to indentation of the vest into the body, caused by too small a body area being impacted and required to absorb the energy of a bullet.
A common problem with prior art ceramic armor concerns damage inflicted on the armor structure by a first projectile, whether stopped or penetrating. Such damage weakens the armor panel, and so allows penetration of a following projectile, impacting within a few centimeters of the first.
The present invention is therefore intended to obviate the disadvantages of prior art ceramic armor, and in a first embodiment to provide an armor plate which is effective against small-caliber fire-arm projectiles, yet is of light weight, i.e, having a weight of less than 45 kg/m
2
(which is equivalent to about 9 lbs/ft ) and low bulk.
In other embodiments the present invention provides an armor plate which is effective against a full range of armor-piercing projectiles from 5.56 mm and even up to 30 mm, as well as from normal small-caliber fire-arm projectiles, yet is of light weight, i.e., having a weight of less than 185 kg/m
2
, even for the heavier armor provided for dealing with 25 and 30 mm projectiles.
A further object of the invention is to provide an armor plate or panel which is particularly effective in arresting a plurality
Fulbright & Jaworski L.L.P.
Johnson Stephen M.
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